Reconciling a complicated God

I was in too much pain to sleep, so I read Jeremiah.

Behold, I will lay before this people stumbling blocks, blocks against which they shall stumble; fathers and sons together, neighbor and friend shall perish. Rejected silver they are called, for the Lord has rejected them...the Lord has rejected and forsaken the generation of His wrath. (6:21, 30; 7:29)

In times of sorrow, suffering, anger, questioning, how do I reconcile verses like these with verses on which I lean on for strength:
  • Behold, I will never leave you nor forsake you (Hebrews 13:5b);
  • Blessed is he whose sins are forgiven, who trespasses are not counted against him (Psalm 32:12);
  • though I walk through the valley of the shadow of death, I will fear no evil, for you are with me (Psalm 23:4);
  • the LORD your God goes with you; he will never leave you nor forsake you. (Deuteronomy 31:6)
  • For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord. (Romans 8:38-39)
How is that the same God we worship for His mercy, love, grace, self-sacrifice, joy, kindness, beauty also be the God who rejects, destroys, causes us to stumble, is angry, just, and perfect?

Am I so arrogant as to think that my sin is forgotten because of any merit of my own? Rather, it is because the Father's gaze is fixed on Christ's sacrifice rather than my piddly, proud, pinching, puny and palinological sin!

Confusing, so confusing. Comments would be much appreciated!